### The parity of the pion from .

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We can determine the internal parity of the pion by studying pion capture by a deuteron, The pion is known to have spin 0, the deuteron spin 1, and the neutron spin . The internal parity of the deuteron is +1. The pion is captured by the deuteron from a 1S states, implying in the initial state. So the total angular momentum quantum number of the initial state is .

So the parity of the initial state is

The parity of the final state is

Therefore,

Because the neutrons are identical fermions, the allowed states of two neutrons are , , , The only state with is the state, so

Jim Branson 2013-04-22